This application claims priority to Japanese patent application serial number 2001-281784, the contents of which are incorporated herein by reference.
1. Technical Field
The present invention relates to die-casting systems and machines that include dies into which molten materials are injected in order to form cast products. In particular, the present invention relates to techniques for opening dies in order to remove cast products from the dies.
2. Description of the Related Art
Apparatus for opening dies after completing a casting process are known. For example, Japanese Laid-Open Patent Publication No. 7-186219 teaches a die-opening apparatus for a die-casting machine. The die-opening apparatus includes a first cylinder and a second cylinder. The first cylinder performs an initial die-opening step. The initial die-opening step requires a relatively high load (great force), but does not require a substantial stroke length. The second cylinder performs a subsequent die-opening step that requires a relatively low load (reduced force) and a relatively long stroke length.
However, in order to enable the first cylinder to extend or project under a high load over a relatively short stroke length, the power of the first cylinder is transmitted to a movable die part via a motion conversion mechanism that is configured as a rack and pinion mechanism. Consequently, the construction of the known die-opening apparatus is rather complicated, which has been a problem of the known die-opening apparatus.
Therefore, it is one object of the present invention to teach improved die-opening apparatus for die-casting systems and machines and to simplify the construction thereof.
According to one aspect of the present teachings, apparatus for opening dies in die-casting systems and machines (hereinafter xe2x80x9cdie-opening apparatusxe2x80x9d) are taught that may include a first cylinder and a second cylinder. The first cylinder may serve to initially open the die. The second cylinder may serve to subsequent open the die after the first cylinder has initially opened the die. The thrust generated by the first cylinder (i.e., the movement of the first cylinder when the first cylinder extends or projects and generates an extending thrust or force) may be directly transmitted to the die in the opening direction of the die so as to open the die.
As a result, the thrust (extending force) generated by the first cylinder can be transmitted or applied to the die without changing the direction of the force. Therefore, the present die-opening apparatus do not require a motion conversion mechanism for converting the direction of the force (thrust) of the first cylinder or for converting the movement (linear extension) of the first cylinder into another type of movement, such as rotation. Therefore, the construction of the present die-opening apparatus is simplified as compared to known die-opening apparatus.
According to another aspect of the present teachings, the first cylinder may be made separately from the die. Therefore, the die may have a simple construction and may be relatively lightweight. Optionally, the first cylinder may be mounted on a movable base that can move or slide relative to a die-casting unit.
According to another aspect of the present teachings, the die may include a first die part that can move relative to a second die part. The thrust generated by the first cylinder may be transmitted or applied to the first die part. Optionally, the first cylinder may transmit the thrust to the first die part via a push pin. The push pin may preferably be slidably inserted into a thorough-hole defined within the second die part. The push pin may be normally held in position by a spring, so as not to contact the first die part when the first cylinder is not being actuated.
According to another aspect of the present teachings, methods for opening a die using a first cylinder and a second cylinder are taught. The first cylinder may serve to perform an initial die opening operation. The second cylinder may serve to perform a subsequent die opening operation. The thrust generated by the first cylinder may be directly transmitted to the die in a die opening direction preferably without converting the thrust (force) into another type of force or into another type of movement.
Additional objects, features and advantages of the present invention will be readily understood after reading the following detailed description together with the claims and the accompanying drawings.